What event marked the launch of the first rover on Mars?

The event that marked the launch of the first rover on Mars was indeed the Pathfinder mission. This mission, which was launched by NASA in 1996 and successfully landed on Mars in 1997, included the Sojourner rover. Sojourner was the very first operational rover on the Martian surface, designed to conduct scientific experiments and transmit data back to Earth. It was a groundbreaking achievement in space exploration, demonstrating the capability to deploy rovers that could navigate the terrain of Mars and analyze its composition.

The other missions listed do not pertain to the first successful rover deployment. The Mars Global Surveyor mission was focused on mapping the geology and topography of Mars, primarily through orbit. The Galileo mission was targeted at studying Jupiter and its moons, while the Cassini mission was dedicated to exploring Saturn and its rings. Therefore, the Pathfinder mission stands out as the pivotal event that introduced rover technology on Mars.